Sumner was the tenth girl selected for the top thirteen on Britain's Next Top Model, Cycle 5. Over her stay, Sumner received three first call-outs and survived two bottom two appearances over Lisa-Ann Hillman and Annaliese Dayes. She placed as the runner-up in the finale where Mecia Simson won.
Winning America's Next Top Model Cycle 18: British Invasion
The judges said of her personality that it "lit up a room", leading to Sumner being labeled "Illuminata" by Tyra Banks herself. Over her stay, Sumner won three challenges and received two first call-outs. In the final judging, the judges selected Sumner over the runner-up Laura LaFrate. Sumner became the fifth winner to have never appeared in the bottom two during her time on Top Model.
Sumner released a single entitled "Aiming For You" on iTunes and her photos for Vogue Italia are featured in the August 2012 issue. She has made billboard advertisements for CoverGirl and for the America's Next Top Model perfume, Dream Come True. She is active in raising funds for Breast Cancer Research with the help of her pink dog, Darcy.[6]
In 2012, Sumner appeared as Deepika Padukone's friend in the Bollywood film Cocktail, including dancing sequences.[citation needed] Sumner, along with co-stars Allison Harvard and Dominique Reighard, was featured and walked in the 25th anniversary of Bench Universe Denim and Underwear Show in September 2012.[7][8] In December of the same year, she was a covergirl for MEG Magazine for their frosty December 2012/January 2013 issue.[9] She also attended a fashion show in Montego Bay for Cycle 19 with the contestants.
In 2023, Sumner made her big screen acting debut in Killington, a dark comedy/horror film by Matt Vita and Mark Dudzinski, co-directed by Frank Perz. The film is currently looking towards a distribution deal in 2024.[10]